Journal of Virology (J Virol)

Publications in this journal

• Article: Tsg101 Interacts with Herpes Simplex Virus 1 VP1/2 and Is a Substrate of VP1/2 Ubiquitin-Specific Protease Domain Activity.

  Martina Caduco, Alessandra Comin, Marta Toffoletto, Denis Munegato, Elena Sartori, Michele Celestino, Cristiano Salata, Cristina Parolin, Giorgio Palù, Arianna Calistri
  Journal of Virology 06/2013; 87(11):6537.
• Article: Polarised cell migration during cell-to-cell transmission of herpes simplex virus in human skin keratinocytes.

  F Abaitua, R Zia, M Hollinshead, P O'Hare
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  ABSTRACT: In addition to transmission involving extracellular free particles, a generally accepted model of virus propagation is one wherein virus replicates in one cell producing infectious particles that transmit to the next cell via cell junctions or induced polarised contacts. This mechanism of spread is especially important in the presence of neutralising antibody and the concept underpins analysis of virus spread, plaque size, viral and host functions and general mechanisms of virus propagation. Here we demonstrate a novel process involved in cell-to-cell transmission of herpes simplex virus (HSV) in human skin cells that has not previously been appreciated. Using time lapse microscopy of fluorescent viruses we show that HSV infection induces the polarised migration of skin cells into the site of infection. In the presence of neutralising antibody, uninfected skin cells migrate to the initial site of infection and spread over infected cells, to become infected in a spatially confined cluster containing hundreds of cells. The cells in this cluster do not undergo cytocidal cell lysis but harbour abundant enveloped particles within cells and cell-free virus within interstitial regions below the cluster surface. Cells at the base and outside the cluster were generally negative for virus immediate-early expression. We further show using spatially separated monolayer assays, that at least one component of this induced migration is the paracrine stimulation of a cytotactic response from infected cells to uninfected cells. The existence of this process changes our concept of virus transmission and the potential functions, virus and host factors involved.
  Journal of Virology 05/2013;
• Article: NS3 of Bluetongue virus interferes with the induction of type I interferon.

  Emilie Chauveau, Virginie Doceul, Estelle Lara, Emmanuel Breard, Corinne Sailleau, Pierre-Olivier Vidalain, Eliane F Meurs, Stéphanie Dabo, Isabelle Schwartz-Cornil, Stéphan Zientara, Damien Vitour
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  ABSTRACT: Upon infection with Bluetongue virus (BTV), an arthropod-borne virus, type I interferon (IFN-I) is produced in vivo and in vitro. IFN-Ι is essential for the establishment of an antiviral cellular response and most if not all viruses have elaborated strategies to counteract its action. In this study, we assessed the ability of BTV to interfere with IFN-Ι synthesis and identified the non-structural viral protein NS3 as an antagonist of the IFN-I system.
  Journal of Virology 05/2013;
• Article: Specific amino acid substitutions in the S protein prevent its excretion in vitro and may contribute to occult hepatitis B virus infection.

  Subhajit Biswas, Daniel Candotti, Jean-Pierre Allain
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  ABSTRACT: Occult hepatitis B virus (HBV) infection (OBI) is defined as low plasma level of HBV DNA with undetectable HBV surface antigen (HBsAg) outside the pre-seroconversion window period. The mechanisms leading to OBI remain largely unknown. The potential role of specific amino acid substitutions in the S protein from OBI on HBsAg production and excretion was examined in vitro. HBsAg was quantified in culture supernatants and cell extracts of HuH-7 cells transiently transfected with plasmids containing the S gene of eight HBsAg+ controls and 18 OBI clones. The intracellular (IC)/extracellular (EC) HBsAg production ratio was ∼1.0 for the majority of controls. Three IC/EC HBsAg patterns were observed in OBI strains clones: pattern 1 defined as IC/EC ratio 1.0 in 5/18 OBI clones; pattern 2 with detectable IC but low or undetectable EC HBsAg (IC/EC: 7.0-800) in 6/18 OBIs; and pattern 3 with both low or undetectable IC and EC HBsAg in 7/18 clones. Intracellular immunofluorescence staining showed that, in pattern 2, HBsAg was concentrated around the nucleus suggesting retention in the endoplasmic reticulum. Substitutions M75T, Y100S or P178R were present in 4/6 pattern 2 OBI clones. Site-directed mutagenesis-corrected mutations reversed HBsAg excretion to pattern 1 and, when introduced in a control clone, induced pattern 2 except for Y100S. In a control and several OBIs, variants of a given quasispecies expressed HBsAg according to different patterns. However, the P178R substitution present in all cloned sequences of two OBI strains may contribute significantly to the OBI phenotype.
  Journal of Virology 05/2013;
• Article: Accessory Genes Confer High Replication Rate of Virulent Feline Immunodeficiency Virus (FIV).

  Ryan M Troyer, Jesse Thompson, John H Elder, Sue Vandewoude
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  ABSTRACT: Feline immunodeficiency virus (FIV) is a lentivirus that causes AIDS in domestic cats, similar to HIV/AIDS in humans. FIV accessory protein Vif abrogates inhibition of infection by cat APOBEC3 restriction factors. FIV also encodes a multifunctional OrfA accessory protein, which has characteristics similar to HIV Tat, Vpu, Vpr, and Nef. To examine the role of vif and orfA accessory genes in FIV replication and pathogenicity, we generated chimeras between two FIV molecular clones with divergent disease potential: a highly pathogenic isolate that replicates rapidly in vitro and is associated with significant immunopathology in vivo, (FIV-C36, referred to as high virulence, or HV-FIV); and a less pathogenic strain (FIV-PPR, referred to as low virulence, or LV-FIV). Using PCR-driven overlap extension, we produced viruses in which vif, orfA or both genes from virulent HV-FIV replaced equivalent genes in LV-FIV. Generation of these chimeras is more straightforward in FIV than in primate lentiviruses, since FIV accessory gene open reading frames have very little overlap with other genes. All three chimeric viruses exhibited increased replication kinetics in vitro compared to LV-FIV. Chimeras containing HV-Vif or Vif/OrfA had replication rates equivalent to virulent HV-FIV parental virus. Furthermore, siRNA knockdown of feline APOBEC3 genes resulted in equalization of replication rates between LV-FIV and LV-FIV encoding HV-FIV Vif. These findings demonstrate that Vif-APOBEC interactions play a key role in controlling replication and pathogenicity of this immunodeficiency-inducing virus in its native host species, and that accessory genes act as mediators of lentiviral strain-specific virulence.
  Journal of Virology 05/2013;
• Article: Contribution of follicular dendritic cells to persistent HIV viremia.

  Jingshan Zhang, Alan S Perelson
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  ABSTRACT: HIV-1 infections cannot be completely eradicated by drug therapy as the virus persists in reservoirs. Low-level plasma viremia has been detected in patients treated for over seven years, but the cellular compartments that support this low-level viremia have not been identified. The decay of HIV-1 during treatment appears to occur in four phases, with the 3(rd) and 4(th) phases occurring when the virus is below the limit of detection of conventional assays. Here we focus on the 3(rd) phase of decay, which has been estimated to have a half-life of 39 months. We show that follicular dendritic cells (FDC), which have been identified as an HIV reservoir, can be the main source of the low-level viremia detected during the 3(rd) phase of decay, and contribute to viremia at even longer times. Our calculations show that the kinetics of leakage of virus from FDC is consistent with three types of available clinical data.
  Journal of Virology 05/2013;
• Article: Comparison of infectious virus in respirable aerosols exhaled by ferrets infected with influenza viruses exhibiting diverse transmissibility phenotypes.

  Kortney M Gustin, Jacqueline M Katz, Terrence M Tumpey, Taronna R Maines
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  ABSTRACT: Influenza viruses pose a major public health burden to communities around the world by causing respiratory infections that can be highly contagious and spread rapidly through the population. Despite extensive research on influenza viruses, the modes of transmission occurring most often among humans are not entirely clear. Contributing to this knowledge gap is the lack of an understanding of the levels of infectious virus present in respirable aerosols exhaled from infected hosts. Here, we use the ferret model to evaluate aerosol shedding patterns and measure the amount of infectious virus present in exhaled respirable aerosols. By comparing these parameters among a panel of human and avian influenza viruses exhibiting diverse respiratory droplet transmission efficiencies, we are able to report that ferrets infected by highly transmissible influenza viruses exhale a greater number of aerosol particles and more infectious virus within respirable aerosols compared to ferrets infected by influenza viruses that do not readily transmit. Our findings improve our understanding of the ferret transmission model and provide support for the potential for influenza virus aerosol transmission.
  Journal of Virology 05/2013;
• Article: Protection by Immunoglobulin Dual Affinity Re-Targeting Antibodies against Dengue Virus.

  James D Brien, Soila Sukupolvi-Petty, Katherine L Williams, Chia-Ying Kao Lam, Michael A Schmid, Syd Johnson, Eva Harris, Michael S Diamond
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  ABSTRACT: Dengue viruses are the most common arthropod-transmitted viral infection, with an estimated 390 million human infections annually and ∼3.6 billion people at risk. Currently, there are no approved vaccines or therapeutics available to control the global dengue virus disease burden. In this study, we demonstrate the binding, neutralizing activity, and therapeutic capacity of a novel bi-specific dual affinity re-targeting (DART) molecule that limits infection of all four serotypes of dengue virus.
  Journal of Virology 05/2013;
• Article: DNA Topoisomerase 1 Facilitates the Transcription and Replication of the Ebola Virus Genome.

  Kei Takahashi, Peter Halfmann, Masaaki Oyama, Hiroko Kozuka-Hata, Takeshi Noda, Yoshihiro Kawaoka
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  ABSTRACT: Ebola virus (EBOV) protein L (EBOL) acts as a viral RNA-dependent RNA polymerase. To better understand the mechanisms underlying the transcription and replication of the EBOV genome, we sought to identify cellular factors involved in these processes via their coimmunoprecipitation with EBOL and by mass spectrometry. Of 65 candidate proteins identified, we focused on DNA topoisomerase 1 (TOP1), which localizes to the nucleus and unwinds helical DNA. We found that, in the presence of EBOL, TOP1 colocalizes and interacts with EBOL in the cytoplasm, where transcription and replication of the EBOV genome occur. Knockdown of TOP1 markedly reduced virus replication and viral polymerase activity. We also found that the phosphodiester bridge-cleaving and recombination activities of TOP1 are required for the polymerase activity of EBOL. These results demonstrate that TOP1 is an important cellular factor for the transcription and replication of the EBOV genome and, as such, plays a key role in the EBOV life cycle.
  Journal of Virology 05/2013;
• Article: The Resistance Protein Tm-1 Inhibits Formation of a Tomato Mosaic Virus Replication Protein--Host Membrane Protein Complex.

  Kazuhiro Ishibashi, Masayuki Ishikawa
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  ABSTRACT: The Tm-1 gene of tomato confers resistance to Tomato mosaic virus (ToMV). Tm-1 encodes a protein that binds ToMV replication proteins and inhibits the RNA-dependent RNA replication of ToMV. The replication proteins of resistance-breaking mutants of ToMV do not bind Tm-1, indicating that the binding is important for inhibition. In this study, we analyzed how Tm-1 inhibits ToMV RNA replication in a cell-free system using evacuolated tobacco protoplast extracts. In this system, ToMV RNA replication is catalyzed by replication proteins bound to membranes, and the RNA polymerase activity is unaffected by treatment with 0.5 M NaCl-containing buffer and remains associated with membranes. We show that in the presence of Tm-1, negative-strand RNA synthesis is inhibited, the replication proteins associate with membranes with binding that is sensitive to 0.5 M NaCl, the viral genomic RNA used as a translation template is not protected from nuclease digestion, and host membrane proteins TOM1, TOM2A, and ARL8 are not co-purified with the membrane-bound 130K replication protein. Deletion of the polymerase read-through domain or of the 3'UTR of the genome did not prevent formation of complexes between the 130K protein and the host membrane proteins, the 0.5 M NaCl-resistant binding of the replication proteins to membranes, and the protection of the genomic RNA from nucleases. These results indicate that Tm-1 binds ToMV replication proteins to inhibit key events in replication complex formation on membranes that precede negative-strand RNA synthesis.
  Journal of Virology 05/2013;
• Article: Crystal structure of the avian astrovirus capsid spike.

  Rebecca M Dubois, Pamela Freiden, Shauna Marvin, Muralidhar Reddivari, Richard J Heath, Stephen W White, Stacey Schultz-Cherry
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  ABSTRACT: Astroviruses are small, nonenveloped, single-stranded RNA viruses that cause diarrhea in a wide variety of mammals and birds. On the surface of the viral capsid are globular spikes that are thought to be involved in attachment to host cells. To understand the basis of species-specificity, we investigated the structure of an avian astrovirus capsid spike and compared it to a previously-reported human astrovirus capsid spike structure. Here we report the crystal structure of the turkey astrovirus-2 (TAstV-2) capsid surface spike domain determined to 1.5 Å resolution and identify three conserved patches on the surface of the spike that are candidate avian receptor-binding sites. Surprisingly, the overall TAstV-2 capsid spike structure is unique, with only distant structural similarities to the human astrovirus capsid spike and other viral capsid spikes. There is an absence of conserved, putative receptor-binding site residues between the human and avian spikes. However, there is evidence for carbohydrate-binding sites in both human and avian spikes, and studies with the human astrovirus-1 (HAstV-1) suggest a minor role for chondroitin sulfate but not heparin in infection. Overall, our structural and functional studies provide new insights into astrovirus host cell entry, species-specificity, and evolution.
  Journal of Virology 05/2013;
• Article: A novel bivalent vaccine based on a PB2-knockout influenza virus protects mice from pandemic H1N1 and highly pathogenic H5N1 virus challenges.

  Ryuta Uraki, Maki Kiso, Kiyoko Iwatsuki-Horimoto, Satoshi Fukuyama, Emi Takashita, Makoto Ozawa, Yoshihiro Kawaoka
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  ABSTRACT: Vaccination is an effective means to protect against influenza virus. Although inactivated and live-attenuated vaccines are currently available, each vaccine has disadvantages (e.g., immunogenicity and safety). To overcome these problems, we previously developed a replication-incompetent PB2-knockout (PB2-KO) influenza virus that replicates only in PB2 protein-expressing cells. Here, we generated two PB2-KO viruses whose PB2-coding regions were replaced with the HA genes of either A/California/04/2009 (H1N1pdm09) or A/Vietnam/1203/2004 (H5N1). The resultant viruses comparably, or in some cases more efficiently, induced virus-specific antibodies in the serum, nasal wash, and bronchoalveolar lavage fluid of mice relative to a conventional formalin-inactivated vaccine. Furthermore, mice immunized with these PB2-KO viruses were protected from lethal challenges with not only the backbone virus strain, but also strains from which their foreign HAs originated, indicating that PB2-KO viruses with antigenically different HAs could serve as bivalent influenza vaccines.
  Journal of Virology 05/2013;
• Article: A carboxy-terminally truncated human CPSF6 lacking residues encoded by exon 6 inhibits HIV-1 cDNA synthesis and promotes capsid disassembly.

  Takanori Hori, Hiroaki Takeuchi, Hideki Saito, Ryuta Sakuma, Yoshio Inagaki, Shoji Yamaoka
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  ABSTRACT: Since HIV-1 replication is modulated at multiple stages by host cell factors, identification and characterization of those host cell factors are expected to contribute to developing novel anti-HIV therapeutics. Previous studies showed that a C-terminally truncated cytosolic form of cleavage and polyadenylation specific factor 6 (CPSF6)-358 inhibits HIV-1 infection through the interference with HIV-1 trafficking to the nucleus. Here we identified and characterized a different configuration of C-terminally truncated human CPSF6 (hCPSF6-375) through a cDNA expression cloning coupled with ganciclovir-mediated lethal selection. Notably, hCPSF6-375, but not mCPSF6-358 as previously reported, remarkably interfered with viral cDNA synthesis after HIV-1 infection. Moreover, we found that hCPSF6-375 aberrantly accelerated the disassembly of the viral capsid in target cells, while CPSF6-358 did not. Sequence comparison of CPSF6-375 and CPSF6-358 cDNAs showed a lack of exon 6 and additional coding sequence for 54 amino acid residues in the C-terminus of hCPSF6-375. Mutational analyses revealed that the residues encoded by exon 6, but not the C-terminal 54 residues in hCPSF6-375, is responsible for impaired viral cDNA synthesis by hCPSF6-375. This is the first report demonstrating a novel mode of HIV-1 inhibition by truncated forms of CPSF6 that involves rapid capsid disassembly and inhibition of viral cDNA synthesis. These findings could facilitate an increased understanding of viral cDNA synthesis in light of the viral capsid disassembly.
  Journal of Virology 05/2013;
• Article: Assessment of the protective effect of IMVAMUNE(R) and ACAM2000(R) vaccines against aerosolised Monkeypox virus in cynomolgus macaques.

  Graham J Hatch, Victoria A Graham, Kevin R Bewley, Julia A Tree, Mike Dennis, Irene Taylor, Simon G P Funnell, Simon Bate, Kimberley Steeds, Thomas Tipton, Thomas Bean, Laura Hudson, Deborah J Atkinson, Gemma McLuckie, Melanie Charlwood, Allen D G Roberts, Julia Vipond
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  ABSTRACT: To support the licensure of a new and safer vaccine to protect people against smallpox, a monkeypox model of infection in cynomolgus macaques, which simulates smallpox in man, was used to evaluate two vaccines, ACAM2000® and IMVAMUNE® for protection against disease. Animals vaccinated with a single immunisation of IMVAMUNE® were not protected completely from severe/lethal infection whereas those receiving either a prime and boost of IMVAMUNE®, or a single immunisation with ACAM2000® were protected completely. Additional parameters including clinical observations, radiographs, viral load in blood, throat swabs and selected tissues, vaccinia virus-specific antibody responses, immunophenotyping, extracellular cytokines levels and histopathology were assessed. There was no significant difference (p>0.05) between the levels of neutralizing antibody in animals vaccinated with a single immunization of ACAM2000® (132 U/ml) and the prime/boost IMVAMUNE® regime (69 U/ml) prior to challenge with monkeypox virus. After challenge there was evidence of viral excretion from the throats of 2 out of 6 animals in the prime/boost IMVAMUNE® group whereas there was no confirmation of excreted live virus in the ACAM2000® group. This evaluation of different human smallpox vaccines in cynomolgus macaques helps to provide information about optimal vaccine strategies in the absence of human challenge studies.
  Journal of Virology 05/2013;
• Article: A chemokine-like viral protein enhances IFN-α production by plasmacytoid dendritic cells but delays CD8+ T cell activation and impairs viral clearance.

  Matthew E Wikstrom, Peter Fleming, Iain Comerford, Shaun R McColl, Christopher E Andoniou, Mariapia A Degli-Esposti
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  ABSTRACT: Murine cytomegalovirus encodes numerous proteins that act on a variety of pathways to modulate the innate and adaptive immune responses. Here, we demonstrate that a chemokine-like protein encoded by murine cytomegalovirus activates the early innate immune response and delays adaptive immunity, thereby impairing viral clearance. The protein, m131/129 (also known as MCK-2), is not required to establish infection in the spleen, however, a mutant virus lacking m131/129 is cleared more rapidly from this organ. In the absence of m131/129 expression there is enhanced activation of dendritic cells (DC), and virus-specific CD8(+) T cells are recruited earlier into the immune response. Viral mutants lacking m131/129 elicited weaker production of IFN-α at 40 hours post-infection, indicating that this protein exerts its effects during early rounds of viral replication in the spleen. Furthermore, while wild-type and mutant viruses activated plasmacytoid dendritic cells (pDC) equally at this time, as measured by the upregulation of costimulatory molecules, the presence of m131/129 stimulated more pDC to secrete IFN-α accounting for the stronger IFN-α response to the wild-type virus. These data provide evidence for a novel immunomodulatory function of a viral chemokine and expose the multi-functionality of immune-evasion proteins. In addition, these results broaden our understanding of the interplays between innate and adaptive immunity.
  Journal of Virology 05/2013;
• Article: The CD225 Domain of IFITM3 is Required for both IFITM Protein Association and Inhibition of Influenza A Virus and Dengue Virus Replication.

  Sinu P John, Christopher R Chin, Jill Perreira, Eric M Feeley, Aaron Aker, George Savidis, Sarah E Smith, Andrew E H Elia, Aaron R Everitt, Mehul Vora, Thomas Pertel, Stephen J Elledge, Paul Kellam, Abraham L Brass
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  ABSTRACT: IFITM3 is an interferon stimulated gene which inhibits the replication of multiple pathogenic viruses in vitro and in vivo. IFITM3 is a member of a large protein super family, whose members share a functionally-undefined area of high amino acid conservation, the CD225 domain. We performed mutational analyses of IFITM3 and identified multiple residues within the CD225 domain, consisting of the first intramembrane domain (IM1) and a conserved intracellular loop (CIL), that are required for restriction of both influenza A virus (IAV) and dengue virus (DENV) infection in vitro. Two phenylalanines within IM1 (F75 and F78) also mediate a physical association between IFITM proteins, and the loss of this interaction decreases IFITM3-mediated restriction. By extension, similar IM1-mediated associations may contribute to the functions of additional members of the CD225 domain family. IFITM3's distal N-terminal domain is also needed for full anti-viral activity, including a tyrosine (Y20), whose alteration results in mislocalization of a portion of IFITM3 to the cell periphery and surface. Comparative analyses demonstrate that similar molecular determinants are needed for IFITM3's restriction of both IAV and DENV. However, a portion of the CIL including Y99 and R87 is preferentially needed for inhibition of the orthomyxovirus. Several IFITM3 proteins engineered with rare single nucleotide polymorphisms demonstrated reduced expression or mislocalization, and these events were associated with enhanced viral replication in vitro, suggesting that possessing such alleles may impact an individual's risk for viral infection. Based on this and other data, we propose a model for IFITM3-mediated restriction.
  Journal of Virology 05/2013;
• Article: Infectious Virion Capture by HIV-1 gp120 Specific IgG from RV144 Vaccinees.

  Pinghuang Liu, Nicole L Yates, Xiaoying Shen, Mattia Bonsignori, M Anthony Moody, Hua-Xin Liao, Youyi Fong, S Munir Alam, R Glenn Overman, Thomas Denny, [......], Punnee Pitisuttithum, Jaranit Kaewkungwal, Sorachai Nitayaphan, Supachai Rerks-Ngarm, David C Montefiori, Peter Gilbert, Nelson L Michael, Jerome H Kim, Barton F Haynes, Georgia D Tomaras
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  ABSTRACT: The detailed examination of the antibody repertoire from RV144 provides a unique template for understanding potentially protective antibody functions. Some potential immune correlates of protection were untested in the correlates analyses due to inherent assay limitations as well as the need to keep the correlates analysis focused on a limited number of endpoints to achieve statistical power. In an RV144 pilot study, we determined that RV144 vaccination elicited antibodies that could bind infectious virions (including the vaccine strains, HIV-1 CM244 and HIV-1 MN, and an HIV-1 expressing transmitted/founder Env B.WITO.c). Among those vaccinees with the highest IgG binding antibody profile, the majority (78%) captured the infectious vaccine strain virus(CM244) while a smaller proportion of vaccinees (26%) captured HIV-1 transmitted/founder Env virus. We demonstrated that vaccine-elicited HIV-1 gp120 antibodies of multiple specificities (V3, V2, conformational C1, and gp120 conformational) mediated capture of infectious virions. Although capture of infectious HIV-1 correlated with other humoral immune responses, the extent of variation between these humoral responses and virion capture indicates that virion capture antibodies occupy unique immunological space.
  Journal of Virology 05/2013;
• Article: Hepatitis C virus infection upregulates CD55 expression on hepatocyte surface and promotes association with virus particles.

  Budhaditya Mazumdar, Hangeun Kim, Keith Meyer, Sandip K Bose, Adrian M Di Bisceglie, Ratna B Ray, Michael S Diamond, John P Atkinson, Ranjit Ray
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  ABSTRACT: CD55 limits excessive complement activation on the host cell surface by accelerating the decay of C3 convertases. In this study, we observed that hepatitis C virus (HCV) infection of hepatocytes or HCV core protein expression in transfected hepatocytes upregulated CD55 expression at the mRNA and protein levels. Further analysis suggested that HCV core or full-length (FL) genome enhanced CD55 promoter activity in a luciferase based assay, which is further augmented in the presence of IL-6. Mutation of the CREB or SP-1 binding site on the CD55 promoter impaired HCV core mediated upregulation of CD55. HCV infected or core transfected Huh7.5 cells displayed greater cell viability in the presence of CD81 and CD55 antibodies and complement. Biochemical analysis revealed that CD55 was associated with cell culture grown HCV after purification by sucrose density gradient ultracentrifugation. Consistent with this, a polyclonal antibody to CD55 captured cell culture grown HCV. Blocking antibodies against CD55 or virus envelope glycoproteins in the presence of normal human serum as a source of complement inhibited HCV infection. The inhibition was enhanced in the presence of both the antibodies and serum complement. Collectively, these results suggest that HCV induces and associates with a negative regulator of the complement pathway, a likely mechanism for immune evasion.
  Journal of Virology 05/2013;
• Article: Virus-Specific Effects of TRIM5αrh RING Domain Functions on Restriction of Retroviruses.

  Xing Li, Jonghwa Kim, Byeongwoon Song, Andres Finzi, Beatriz Pacheco, Joseph Sodroski
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  ABSTRACT: The tripartite motif protein TRIM5α restricts particular retrovirus infections by binding to the incoming capsid and inhibiting the early stage of virus infection. The TRIM5α RING domain exhibits E3 ubiquitin ligase activity and assists the higher-order association of TRIM5α dimers, which promotes capsid binding. We characterized a panel of RING domain mutants of the rhesus monkey TRIM5α (TRIM5αrh) protein. The RING domain function that significantly contributed to retroviral restriction depended upon the restricted virus. The E3 ubiquitin ligase activity of the RING domain contributes to the potency of HIV-1 restriction. Nonetheless, TRIM5αrh mutants without detectable E3 ubiquitin ligase activity still blocked reverse transcription and inhibited HIV-1 infection at a moderate level. When TRIM5αrh capsid binding was weakened by substitution of a less efficient B30.2/SPRY domain, the promotion of higher-order association by the RING domain was more important to HIV-1 restriction than its E3 ubiquitin ligase activity. For the restriction of N-tropic murine leukemia virus (N-MLV) and equine infectious anemia virus (EIAV) infection, promotion of higher-order association represented the major contribution of the RING domain. Thus, both identity of the target virus and the B30.2/SPRY domain-mediated affinity for the viral capsid determine the relative contribution of the two known RING domain functions to TRIM5α restriction of retrovirus infection.
  Journal of Virology 05/2013;
• Article: Functional similarity between E6 proteins of cutaneous HPVs and adenovirus E1A tumor-restraining module.

  Mohan Kuppuswamy, T Subramanian, Elizabeth Kostas-Polston, S Vijayalingam, Ling-Jun Zhao, Mark Varvares, G Chinnadurai
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  ABSTRACT: The adenovirus E1A C-terminal region restrains oncogenic transformation through interaction with three distinct cellular protein complexes that include the DYRK1A/1B/HAN11 complex. The E6 proteins of beta-HPVs also interact with the DYRK1/HAN11 complex. A variant of HPV5 E6 frequently found in epidermodysplasia verruciformis skin lesions interacted less efficiently with DYRK1A/HAN11. The E6 variant and E7 of HPV5 efficiently co-immortalized primary epithelial cells suggesting naturally arising variants may contribute potential oncogenic activities of beta-HPV E6 proteins.
  Journal of Virology 05/2013;